Lithium is rare non-ferrous metal, which has been widely used in a secondary battery, a special glass, a single-crystal oxide, an aircraft, a spring material, etc. Global demands for lithium have recently increased along with demand expansion of information technology devices. Demands for the lithium will further increase. Producing countries of the lithium are concentrated, and it is therefore desirable to recover the lithium in a stable manner in countries having no mineral resources for lithium.
As a conventional lithium recovery method, there is for an example a method in which adsorption and desorption of lithium ion in an aqueous solution are carried out by using manganese oxide electrodes, which have been obtained by condensing lithium or magnesium from lithium-bearing manganese oxide or magnesium-bearing manganese oxide, respectively, and varying an applied voltage (see Japanese Patent Provisional Publication No. H06-088277). In addition, as a conventional lithium recovery method, there is for an example a method comprising the steps of bringing an adsorbent, which has been prepared from raw materials of β-diketone, neutral organic phosphorous compound and vinyl monomer having a cyclic structure, into contact with an aqueous solution containing at least lithium, sodium and calcium, in a pH value of 7 or more of the solution to cause metallic components in the solution to be adsorbed on the above-mentioned adsorbent, and then bringing them into contact with water having a pH value of 4±1.5 to desorb the lithium (see Japanese Patent Provisional Publication No. 2009-161794).